The NTP Mutagenesis Testing Programs are generating large volumes of data and experimental information on all chemicals which will be tested for mutagenicity. A computerized data base management system is needed to capture this information in an interactive mode in the testing laboratory, store, process, and analyze the data, and provide summary analyses to the experimenter and to the CGTB project officers. This system will also allow the CGTB staff to follow the course of testing with time in the large number of laboratories regardless of the mutagenicity test system being used. The PROPHET system developed and managed under contract to NIH/DRR, has been selected. It is being adapted to serve as the CGTB data base management system.